Luminescent tube



July 2 1929- I c. B. LANCASTER 1,721,700

LUMINESCENT TUBE Filed June 1, 1927 2 a F1126 Q5" Car/.25. Larzcaafera INVENTOR @QW/ZTQJATTORNEY Patented July 23, 19 29.

UNITED STATES CARL B. LANCASTER, OI ALAKEDA, CALIFORNIA.

LUIINESCEN'T TUBE.

Application filed June 1, 1927. Serial llo. 185,864.

This invention relates to improvements in luminescent tubes and more particularly to tubes usin neon gas, mercury vapor and mixtures o the same, and other luminescent media for signs and mass illumination.

It is general practice in the use of luminescent tubes for advertising purposes, to bend the glass tube into the contour or outline of the characters that it is desired to display. This method presents several serious disadvantages, among which is the mechanical difliculty of bending glass tubing, especially in the formation of small lettering. It being practically impossible to form letters less than four or five inches in height, am evenin letters of greater height, the char: tors are clumsy and because of the necessary of overlayingtubes, or presenting one part of the tube behind another, such characters are only clearly legible by a full front view. Another disadvantage is the cost of constructing and mounting such letters and combining them in signs.

The principal object of this invention is to overcome the above disadvantages in the use of luminescent tubes, with the further ob\ ject of presenting neonand similar gas signs in a new form, in which small lettering, reading matter, illustrations and similar charac- 'ters may be presented in small dimensions with clean cut definition, and with a degree of detail heretofore unknown to me in this art. Other objects and advantages will appear as this description progresses.

In this specification and the annexed drawings, the invention is illustrated in the form considered to be the best, but I do not wish to be understood as confining it to this form because it may be embodied in other forms,

and it is also to be understood that in and by the claims following the description it is desired to cover the invention in whatsoever form it may be embodied.

In the accompanying one sheet of drawings, Fig. 1 is an end view of a cabinet sign constructed in accordance with this invention, the end of the cabinet being omitted and other parts shown partially in section.

. Fig. 2 is an enlarged detail in rear elevation of a bank of luminescent tubes showing the manner of constructing and arrangin the same enbanc. Fig. 3 is a longitudina section viewed from above of a duplex sign constructed in accordance with this invention, the cabinet top being omitted.

In detail the construction illustrated in the drawings, which is designed particularly for interior signs, consists of an enclosing or cabinet composed of the bottom 1, the top 2, the back 4 to which the top 2 is at 5, and the front frame 6 and the en 7, constructed and jointed together to form an ornamental enclosin cabinet. In the present instance this ca inet is constructed of wood, but it may be composed of sheet metal or other materials best suited to the use to which it is to be put and the conditions under which it is expected to operate. The cabinet should be properly vented as at 4' for the esback 4 of the cabinet to receive the lug 11 connected in the circuit 12 with the a ternating current generator 13. Commercial current varies 1n voltage, amperage and other conditions, and the transformer 9 will vary accordingly, to meet the nature of the currentsupply. Y

The front frame 6 surrounds an opening leading into the interior of the cabinet. This opening is closed by the sign 14 fitting within the guide slots formed in the frame 6.

one ofthe ends of. the frame being slotted entirely through to permit the insertion and withdrawal of the signl l. This sign is in serted in front of the bank of tubes 15 supported in the brackets 8-8 on opposite sides of the cabinet, in which it, is eld by the. strips 16-16 screwed thereto to confine the tubes enbanc. In Fig. 1, the reflecting medium 17, shown in dotted lines, such as a mirror, may be added and mounted in the brackets 88 behind the bank of tubes 15,. for the purpose of reflecting the luminescence of the tubes through the sign 14 or other transparency in the front of the cabinet.

The manner of bending and arranging the luminescent tube, that must be continuous between the electrodes at its opposite ends, presents considerable mechanical dlficulty,

the overcoming of which presents a novel feature of this invention. I

In the use of neon and mixtures thereof, and similar gases for lumlneseence, a continuous tube such as is provided on its ing. A radius longer than necessary is Opposite ends with the bulbous electrode chambers such as 18-18, see Fig. 2. Within these enlarged chambers, the electrodes 1919 are suitably mounted and have the protruding terminal wires 2020, that are properly connected in circuit with the high tension current of the transformer at the binding posts 21-21, after the tube has been properly prepared for operation.

The preparation of the tube consists in attaching a vacuum pump or other exhausting means with the interior thereof, for instance, at the point 22, and exhausting the tubes of all atmosphere and occluded gases from the walls of the tube and the surfaces of the electrodes l919', by any of the accepted processes in the art of preparing luminescent tubes. After the interior of the tube has been cleansed, the connection at 22 is fused oil to preserve the vacuum created within the tube. The neon or other material is then introduced through the tap 23, previously connected thereto, until the necessary quantity of neon has been introduced w1th-.

in the tube when it is then fused on at 23, and the tube is then ready for the application of the high tension. current that will render the gaseous medium confined within the tube 15, luminescent. This preparation of the tube is common practice and no claim of novelty is made therefor, noris this invention intended to be limited to any particular process of'preparation or purification of the tube, since there are many processes now available for that purpose.

So far as I am aware, the following meth- 0d of forming and arranging the tube enbanc is novel. It is accomplished substantially as follows: The tube 15 of the desired length and diameter is heated in a suitable flame and bent back upon itself to form the return bend 23 adjacent its end. It is again heated and the return bend is formed at 24. This second bend is given a slight angular drop and then forced back to aposition immediately beneath the first length 15 to form the length 15, extending under it to the thirdret-urn bend 25, that is similar to 24, and starts the straight length of the tube 15 'beneath and iii-vertical alinement with the tube 15 to the similar return bend 26 with the return length 15, and so continuing until the desired mass of tubes within the bank is obtained, when the tube is again bent back upon itself as at 27 with a [bend similar to 23 and is sealed or welded to the terminal bulb 18'. The bulb 18 is vsimilarly sealed to the opposite end of the wasteful of material and unduly lengthens the circuit of the energizing current. Such dimensions are known to those skilled in this art and therefore are not specifically given herein, since they may be variedto suit conditions.

The prime requisite for the purposes of this invention are to form a bank of tubes set in vertical and horizontal alinement such as indicated in Figs. 1 and 2,.as close together as they may be placed and avoid puncturing and short circuiting of the cur rent While maintaining the effect of a mass of illumination having a horizontally ribbed efi'ect.

The sign consists of transparent glass, having an opaque background outlining the legend to be displayed, or it may be a stencil of any suitable opaque material, such as cardboard, stencil board, metal, or the like, having the desired reading or. advertising matter perforated entirely therethrough.

Fig. 3 is a modified structure for the purpose of forming a duplex sign for utilizing both planes of the bank of tubes. It consists of an enclosing case having the bottom 30, the top not shown, the ends 32 and 33 and the front and back frames 34-435, properly grooved to hold the signs 36 and 37 therein. The bank of tubes 38 is constructed as previously described and islocated between the signs 36 and 37. The bank of tubes is held between the clamping strips 39-39 attached to the bottom 30 of the enclosing cabinet. -Where it is desired to reduce the dimensions of this cabinet, the transformer and other electrical connection may be remotely located and the current carried to the cabinet over properly insulated wires. The obvious advantage of this duplex form of sign is the utilization of both sides of the banlrof tubes for the reading matter contained within the signs 36 and 37.

ere it is desired to give contrasting colors, the bank of tubes may be divided longitudinally with one bank located above another, each color having its independent circuit of high tension current, with appropriate electrodes on the opposite ends of each tube. By this arrangement, the popular colors of neon red and blue, the latter being produced by a mixture of neon gas with mercury vapor, and such other color contrasts are available, by tinted tubes, in form- 12 mg a bank or banks of tubes that will project their luminoscity through the signs exposed thereover.

- This bank of tubes, especially when lueninescentwith neon gas, is not to be confused with internally lighted enclosures using incandescent or other illuminants. Neon and neon gas mixtures have an inherent quality of not diffusing their light. Other means of illuminating the sign 14 are not to be com pared with the improved eifects attained by this invention which solves the problem of small characters and small details in neon signs, the present limitations of which were previously set forth herein.

Having thus described this invention what I claim and'desire to secure by Letters Patent. is:

1. A tube bank comprising a continuous luminescent tube bent back and forth upon itself to form a bank of tube lengths in approximate contact with each other, the outside diameter of the return bends bein wider than the width of two tubes an drop ed at an angle, whereby the said tube lengt s forming the bank between said bends lie in superposed, parallel relation in a flat plane.

2. A sign comprising a sign plate to be illuminated, a continuous luminescent tube bent back and forth upon itself to form a bank of tube lengths in approximate contact with each other, the outside diameter of the return bends being wider than the width of two tubes and dropped at an angle, whereby the said tube len hs forming the bank between said bends ie in superposed parallel relation in a fiat plane. V

In witness whereof I have hereunto afiixed my signature.

CARL B. LANCASTER. 

